Dual lumen cannula

ABSTRACT

A dual lumen coaxial cannula assembly includes a first infusion tube having a first elongate body defining a first lumen therethrough and a second drainage tube co-axially aligned with the first infusion tube and having a second elongate body with a second lumen defined by a space between the first infusion tube and second drainage tube. A connector is removably attached to the first infusion tube and the second drainage tube for coupling the dual lumen coaxial cannula to an extracorporeal blood circuit. The first infusion tube and the second drainage tube include a plurality of infusion and drainage apertures, respectively, provided at the distal end and extending through the sidewall of the first infusion tube and the drainage tube, respectively.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation application of U.S.application Ser. No. 17/518,224, filed Nov. 3, 2021, which is acontinuation application of U.S. application Ser. No. 16/404,317, filedMay 6, 2017, now U.S. Pat. No. 11,179,510, which is a continuationapplication of U.S. patent application Ser. No. 15/720,005, filed Sep.29, 2017, now U.S. Pat. No. 10,279,101, which is a continuationapplication of U.S. patent application Ser. No. 14/869,506, filed Sep.29, 2015, now U.S. Pat. No. 9,782,534, which is a continuationapplication of U.S. patent application Ser. No. 13/718,110, filed Dec.18, 2012, now U.S. Pat. No. 9,168,352, which claims priority to U.S.Provisional Patent Application No. 61/577,257, filed Dec. 19, 2011,entitled “Dual Lumen Cannula”, the entire disclosures of which areincorporated by reference herein.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates, in general, to devices and methods forassisting a patient's heart with a cannula. More specifically, thepresent invention is related to devices and methods for assisting apatient's heart with a cannula where the cannula is of sufficient lengthto, for example, extend from the patient's internal jugular vein to thepulmonary artery.

Description of the Related Art

Traditional cannulae used for patient life support generally involvesingle lumen cannulae at multiple insertion sites, high volume circuits,and cannulae that are not capable of long-term use. Multiple insertionsites increase the risk of bleeding, vessel damage, infection, as wellas pain and discomfort to the patient. These cannulae are designed andbuilt for short-term acute therapies. Additionally, traditional cannulaeusually require access sites located in the patient's groin area nearthe right or left femoral veins.

Patients with severe right-sided circulatory and/or right-sidedventricular failure have significantly high mortality and morbiditycaused by a multitude of factors in multiple patient populations.Historically, Right Ventricular Assist Devices (RVADs) and LeftVentricular Assist Devices (LVADs) have been adapted for use on surgicalpatients without a percutaneous or catheter lab option available. Thesesurgical RVADs have been applied on patients with right inferiormyocardial infarction, acute right-sided ischemic myocardial infarctions(with large left and right propagation), cardiogenic shock, LVAD-createdright ventricular dysfunction, post-transplant right ventricularfailure, and pulmonary hypertension. Acute myocardial infarction andcardiogenic shock have been treated with intra-aortic balloon pumps andmaximal inotropic support, to which many patients become refractory.Surgically implanted LVADs can create a significant septal shift thatleads to a dynamic change in the Starling curve that abruptly placespatients into severe right ventricular failure. Patients can limitpost-transplant survival bridged to transplant to/from an RVAD withsevere right ventricular failure. Secondary pulmonary hypertension leadsto an exacerbation of right ventricular failure in acute and chronicsituations, which may be treated with RVADs.

The foregoing conventional devices do not have the capability to reachthe pulmonary artery (PA) from the internal jugular vein via apercutaneous insertion. Some traditional cannulae are inserted into thepatient's heart through a direct access point in the patient's right orleft femoral vein. Alternatively, traditional RVADs have a cannulaeither primarily placed in the PA or a graft sewn onto the PA, then acannula inserted through the graft. The assembly can then be visualizedin the PA via fluoroscopy and X-Ray with the aid of distal markers inthe cannula, verifying the proper orientation of the outflow to thepatient. In these embodiments, the patient's torso length can limit theability to access the PA via percutaneous insertion. If a cannula is notof a proper length, the interventional procedure may not unload theright ventricle, which leads to an increase of morbidity and mortality.

Furthermore, traditional venoarterial extracorporeal membraneoxygenation (VA ECMO) is the current standard of care used to treatright ventricular failure and respiratory failure percutaneously. VAECMO procedure draws blood from the right atrium and pumps it through anoxygenator and back into the arterial circulation via the femoralartery. VA ECMO bypasses the lungs and the heart completely. Therefore,residual blood is left stagnant in both the heart and lungs potentiallyleading to thrombosis and an inadequately unloaded right ventricle.Additionally, the arterial cannulation can lead to problems includingbut not limited to bleeding, stroke, and infection.

SUMMARY OF THE INVENTION

In view of the foregoing, there is a need for a dual lumen cannula witha single insertion point. There is an additional need for a dual lumencannula that eliminates multiple access sites, reduces bleeding, vesseldamage, and infection, as well as pain and discomfort to the patient.Furthermore, there exists a need for a dual lumen cannula that enablespatients to be ambulatory with access sites provided in the neck areainstead of the groin.

In one embodiment, a dual lumen coaxial cannula assembly includes afirst infusion tube having a first elongate body defining a first lumentherethrough and a second drainage tube co-axially aligned with theinfusion tube and having a second elongate body with a second lumendefined by a space between the first infusion tube and second drainagetube. The first infusion tube may have a proximal end, a distal end, anda sidewall extending circumferentially therebetween. A first connectorportion may be provided at the proximal end of the first infusion tubefor coupling the first insertion tube to a connector. The seconddrainage tube may have a proximal end, a distal end, and a sidewallextending circumferentially therebetween. A second connector portion maybe provided at the proximal end of the second drainage tube for couplingthe second drainage tube to the connector. In accordance with anotherembodiment, a connector may be removably attached to the first connectorportion and the second connector portion for coupling the first infusiontube and the second drainage tube to an extracorporeal blood circuit.

According to another embodiment, the first infusion tube may include aplurality of infusion apertures provided at the distal end. The infusionapertures may extend through the sidewall of the first infusion tube.Similarly, the second drainage tube may include a plurality of drainageapertures provided at the distal end, the drainage apertures extendingthrough the sidewall of the second drainage tube. The plurality ofinfusion apertures may extend through the sidewall of the first infusiontube in a direction perpendicular to a longitudinal axis of the firstinfusion tube. In a similar manner, the plurality of drainage aperturesmay extend through the sidewall of the second drainage tube in adirection perpendicular to a longitudinal axis of the second drainagetube. Alternatively, the plurality of infusion apertures may extendthrough the sidewall of the first infusion tube at an acute or obtuseangle with respect to a longitudinal axis of the first infusion tube.Similarly, the plurality of infusion apertures extends through thesidewall of the first infusion tube at an acute or obtuse angle withrespect to a longitudinal axis of the first infusion tube.

In another embodiment, a wire mesh basket is provided inside the firstlumen at a location surrounding the plurality of infusion apertures forsupporting and preventing collapse of the sidewall of the first infusiontube. In a similar manner, a wire mesh basket is provided inside thesecond lumen at a location surrounding the plurality of drainageapertures for supporting and preventing collapse of the sidewall of thesecond drainage tube. A reinforcing coil may extend from the proximalend to the distal end of one or both of the first infusion tube and thesecond drainage tube. The reinforcing coil desirably extends in ahelical manner along the length of one or both of the first infusiontube and the second drainage tube.

In accordance with another embodiment, the connector may further includea distal aperture in fluid communication with an inlet portion and anoutlet portion, and a barbed fitting on the inlet portion and the outletportion for connecting an infusion line and a drainage line to theconnector. The dual lumen coaxial cannula may be adapted for insertinginto an internal jugular vein of a patient. In another embodiment, thedual lumen coaxial cannula may be adapted for maneuvering through thepatient's vasculature such that the first distal end of the firstinfusion cannula is at least within proximity of the patient's pulmonaryartery and such that the second distal end of the second drainagecannula is at least within proximity of the patient's right atrium.

According to a further embodiment, a method of assisting a patient'sheart may include the step of providing a dual lumen coaxial cannulaassembly having a first infusion tube having a first elongate bodydefining a first lumen therethrough and a second drainage tube coaxiallyaligned with the infusion tube and having a second elongate body with asecond lumen defined by a space between the first infusion tube andsecond drainage tube. The first infusion tube may have a proximal end, adistal end, and a sidewall extending circumferentially therebetween. Afirst connector portion may be provided at the proximal end of the firstinfusion tube for coupling the first insertion tube to a connector. Thesecond drainage tube may have a proximal end, a distal end, and asidewall extending circumferentially therebetween. A second connectorportion may be provided at the proximal end of the second drainage tubefor coupling the second drainage tube to the connector. In accordancewith another embodiment, a connector may be removably attached to thefirst connector portion and the second connector portion for couplingthe first infusion tube and the second drainage tube to anextracorporeal blood circuit. The method may further include the step ofinserting the dual lumen coaxial cannula into an internal jugular veinof the patient, wherein the dual lumen coaxial cannula has a length toextend from the patient's neck area to the patient's heart. The methodmay also include the step of maneuvering the dual lumen coaxial cannulathrough the patient's vasculature such that the first distal end of thefirst infusion cannula is at least within proximity of the patient'spulmonary artery and such that the second distal end of the seconddrainage cannula is at least within proximity of the patient's rightatrium. In another embodiment, the method may also include the steps ofconnecting the connector to a blood pump for establishing rightventricular support and inserting a guidewire to guide the dual lumencoaxial cannula during the maneuvering step. Blood from the blood pumpmay be delivered to the patient's pulmonary artery through the pluralityof infusion apertures of the first infusion tube. Desirably, blood maybe withdrawn from the patient's right atrium through the plurality ofdrainage apertures of the second drainage cannula.

Further details and advantages of the present invention will beunderstood from the following detailed description read in conjunctionwith the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view of one embodiment of a coaxial cannula shown with aconnector.

FIG. 2 is a side view of the coaxial cannula shown in FIG. 1.

FIG. 3 is a top view of one embodiment of an infusion cannula.

FIG. 4 is a cross-sectional view of detail A shown in FIG. 3.

FIG. 5 is a top view of one embodiment of a drainage cannula.

FIG. 6 is a cross-sectional view of detail B in FIG. 5.

FIG. 7 is a top cross-sectional view of the coaxial cannula taken alongline A-A in FIG. 2.

FIG. 8 is a cross-sectional view of detail C in FIG. 7, illustrating atransition portion at a distal end of a drainage cannula of the coaxialcannula.

FIG. 9 is a perspective view of a connector shown coupled to a coaxialcannula according to another embodiment.

FIG. 10 is a rear perspective view of the coaxial cannula shown in FIG.9.

FIG. 11 is a schematic view of one embodiment of a coaxial cannulapositioned in the superior vena cava of a body of a patient.

FIG. 12 is a schematic view of one embodiment of a coaxial cannulapositioned inside a patient's heart.

DETAILED DESCRIPTION OF THE INVENTION

For purposes of the description hereinafter, spatial orientation terms,if used, shall relate to the referenced embodiment as it is oriented inthe accompanying drawing figures or otherwise described in the followingdetailed description. However, it is to be understood that theembodiments described hereinafter may assume many alternative variationsand embodiments. It is also to be understood that the specific devicesillustrated in the accompanying drawing figures and described herein aresimply exemplary and should not be considered as limiting.

Referring to the drawings, in which like reference characters refer tolike parts throughout the several views thereof, various embodiments ofa coaxial, dual lumen cannula 10 (hereinafter referred to as “coaxialcannula 10”) are shown. With initial reference to FIGS. 1-2, theassembled coaxial cannula 10, according to one embodiment, generallyincludes a first infusion tube 12 having a first length and a seconddrainage tube 14 having a second length. The first length of the firstinfusion tube 12 is greater than the second length of the seconddrainage tube 14.

The first infusion tube 12 is disposed within the second drainage tube14 in a coaxial arrangement centered about a central axis 16. Each ofthe first infusion tube 12 and the second drainage tube 14 has a firstcircumference defining a first lumen and a second circumference defininga second lumen, respectively. The first circumference of the firstinfusion tube 12 is smaller than the second circumference of the seconddrainage tube 14 such that the first infusion tube 12 may be placedwithin the second lumen of the second drainage tube 14. One or both ofthe first infusion tube 12 and the second drainage tube 14 may bemanufactured from a medical-grade material such as polyurethane.Alternatively, the tubes may be made from PVC or silicone, and may bedip molded, extruded, co-molded, or made using any other suitablemanufacturing technique.

The coaxial cannula 10 has sufficient placement flexibility adapted forplacement of the coaxial cannula 10 within a patient's body. Desirably,a vascular insertion site is provided at the internal jugular vein onthe patient's neck area. The coaxial cannula 10 is adapted for placementabove or below the right atrium of the patient's heart. The coaxialcannula 10 may be used with an introducer to guide the placement of thecoaxial cannula 10 as it is inserted within the patient's body.

With continuing reference to FIGS. 1 and 2, the coaxial cannula 10 isdesigned to withdraw blood directly from the patient's heart and returnblood back into the patient's heart. The function of the first infusiontube 12 is to deliver blood into the blood stream of the patient, whilethe function of the second drainage tube 14 is to drain the blood fromthe patient's bloodstream as will be described hereafter.

A plurality of infusion apertures 18 is provided at a distal end of thefirst infusion tube 12. The plurality of infusion apertures 18 isdesirably arranged in a circular pattern extending around the outercircumference of the first infusion tube 12. In some embodiments, theplurality of infusion apertures 18 may be disposed in multiple groupsprovided at various sites on the first infusion tube 12. Similarly, thesecond drainage tube 14 includes a plurality of drainage apertures 20provided at a distal end of the second drainage tube 14. The pluralityof drainage apertures 20 is desirably arranged in a circular patternextending around the outer circumference of the second drainage tube 14.In alternative embodiments, the plurality of drainage apertures 20 maybe arranged in groups disposed at various sites along the length of thesecond drainage tube 14. The infusion apertures 18 are separated fromthe drainage apertures 20 by a distance D. In different embodiments ofthe coaxial cannula 10, the separation of infusion apertures 18 fromdrainage apertures 20 determines the amount of mixing of oxygenatedblood and unoxygenated blood. This distance may vary based on the ageand size of the patient, as well as the desired flow rates during themedical procedure where the coaxial cannula 10 is used. For example, acoaxial cannula 10 having a specific overall length and diameter, alongwith a desired pattern and distance between the infusion apertures 18and the drainage apertures 20 may be selected based on age and/or sizeof the patient.

With continuing reference to FIGS. 1 and 2, a connector 22 is providedat the proximal end of the coaxial cannula 10. The connector 22 includesan inlet portion 24 in fluid communication with the first infusion tube12 to transfer blood from a blood pump (not shown) to the first infusiontube 12. An outlet portion 26 of the connector 22 is in fluidcommunication with the second drainage tube 14 to transfer blood fromthe second drainage tube 14 to the blood pump. The outlet portion 26 andthe inlet portion 24 of the connector 22 are arranged such that thefluid pathways leading from the second drainage tube 14 and to the firstinfusion tube 12 transition from a coaxial arrangement at a distal endof the connector 22 to an axially-offset arrangement at a proximal endof the connector 22. Details of the connector 22 construction will bediscussed in greater detail below.

With reference to FIGS. 3-4, and with continuing reference to FIGS. 1and 2, the first infusion tube 12 is illustrated separate from thecoaxial cannula 10. The first infusion tube 12 has a first elongate body28 having a working length of, for example, around 21 cm. The firstelongate body 28 of the first infusion tube 12 is substantiallycylindrical and extends from a first proximal end 30 to a first distalend 32. The first elongate body 28 includes a first lumen 29 extendingthroughout the entire length of the first infusion tube 12. The firstproximal end 30 includes a first connector portion 34 for coupling thefirst infusion tube 12 to the inlet portion 24 of the connector 22. Thefirst elongate body 28 of the first infusion tube 12 has a hollowstructure defined by a first sidewall 36 extending circumferentiallyabout the first elongate body 28. The first sidewall 36 has asubstantially constant thickness throughout the length of the firstelongate body 28, with a first tapering section 38 at the first distalend 32 of the first elongate body 28. At the first proximal end 30 ofthe first elongate body 28, the first sidewall 36 gradually increases inthickness before transitioning into the first connector portion 34. Thefirst tapering section 38 located at the first distal end 32 has athinner first sidewall 36 but retains the internal diameter of the firstinfusion tube 12. The first tapering section 38 enables easier insertionof the first infusion tube 12 into the patient's body.

With specific reference to FIG. 4, the first distal end 32 of the firstinfusion tube 12 is shown. The plurality of infusion apertures 18 isprovided at the first distal end 32 of the first infusion tube 12. Theplurality of infusion apertures 18 extends circumferentially around thefirst distal end 32. Each infusion aperture 18 has a diameter of, forexample, about 1 mm. The plurality of infusion apertures 18 may bearranged in an alternating pattern of axially offset rows of infusionapertures 18 arranged around the circumference of the first infusiontube 12. Each of the plurality of infusion apertures 18 extends throughthe thickness of the first sidewall 36. The infusion apertures 18illustrated in FIGS. 3 and 4 extend through the first sidewall 36 in adirection perpendicular to a longitudinal axis of the first elongatebody 28. Alternatively, the plurality of infusion apertures 18 mayextend through the thickness of the first sidewall 36 in an angledmanner with respect to the longitudinal axis of the first elongate body28. For example, the plurality of infusion apertures 18 may be arrangedat an acute or obtuse angle with respect to a cross-sectional plane ofthe first infusion tube 12 extending perpendicular to the longitudinalaxis of the first elongate body 28. In some embodiments, a wire meshbasket is provided inside the first lumen 29 of the first infusion tube12 at a location surrounding the infusion apertures 18. The wire meshbasket supports and prevents the first sidewall 36 from collapsing dueto being weakened by the formation of the plurality of infusionapertures 18. In one embodiment, one or more sensors (not shown) may beprovided at first distal end 32 of the first infusion tube 12. Thesensor(s) may be adapted for measuring, for example, local bloodpressure and/or oxygen concentration.

The total cross-sectional area of the plurality of infusion apertures 18is desirably approximately equal to or greater than the cross-sectionalarea of the first lumen 29. If the cross-sectional area of the pluralityof infusion apertures 18 is less than the cross-sectional area of thefirst lumen 29, an undesirable pressure drop may occur. This pressuredrop reduces the flow throughput within the first lumen 29 and impairsthe efficiency of the first infusion tube 12. Desirably, the total crosssectional area of the plurality of infusion apertures 18 exceeds thecross sectional area of the first lumen 29 such that if one or more ofthe infusion apertures 18 becomes clogged, the total cross sectionalarea of the remaining infusion apertures 18 is equal to or greater thanthe cross sectional area of the first lumen 29. In this manner, theblood flow through the first lumen 29 is maximized even if one or moreof the infusion apertures 18 become clogged.

With reference to FIGS. 5-6, and with continuing reference to FIGS. 1and 2, the second drainage tube 14 is illustrated separate from thecoaxial cannula 10. The second drainage tube 14 has a second elongatebody 40 having a working length of, for example, around 12 cm. Thesecond elongate body 40 of the second drainage tube 14 is substantiallycylindrical and extends from a second proximal end 42 to a second distalend 44. The second elongate body 40 includes a second lumen 46 extendingthroughout the entire length of the second drainage tube 14. The secondproximal end 42 includes a second connector portion 47 for coupling thesecond drainage tube 14 to the outlet portion 26 of the connector 22.The second elongate body 40 of the second drainage tube 14 has a hollowstructure defined by a second sidewall 48 extending circumferentiallyabout the second elongate body 40. The second sidewall 48 has asubstantially constant thickness throughout the length of the secondelongate body 40, with a second tapering section 50 at the second distalend 44 of the second elongate body 40. At the second proximal end 42 ofthe second elongate body 40, the second sidewall 48 gradually increasesin thickness before transitioning into the second connector portion 47.The second tapering section 50 located at the second distal end 44 has athinner second sidewall 48 but retains the internal diameter of thesecond lumen 46. The second tapering section 50 enables easier insertionof the second drainage tube 14 into the patient's body.

With specific reference to FIG. 6, the second distal end 44 of thesecond drainage tube 14 is shown. The plurality of drainage apertures 20is provided at the second distal end 44 of the second drainage tube 14.The plurality of drainage apertures 20 extends circumferentially aroundthe second distal end 44. Each drainage aperture 20 has a diameter of,for example, about 1.5 mm. The plurality of drainage apertures 20 may bearranged in an alternating pattern of axially offset rows around thecircumference of the second drainage tube 14. Each of the plurality ofdrainage apertures 20 extends through the thickness of the secondsidewall 48. The drainage apertures illustrated in FIGS. 5 and 6 extendthrough the second sidewall 48 in a direction perpendicular to alongitudinal axis of the second elongate body 40. Alternatively, theplurality of drainage apertures 20 may extend through the thickness ofthe second sidewall 48 in an angled manner with respect to thelongitudinal axis of the second elongate body 40. For example, theplurality of drainage apertures 20 may be arranged at an acute or obtuseangle with respect to a cross-sectional plane of the second drainagetube 14 extending perpendicular to the longitudinal axis of the secondelongate body 40. In some embodiments, a wire mesh basket is providedinside the second lumen 46 of the second drainage tube 14 at a locationsurrounding the drainage apertures 20. The wire mesh basket supports andprevents the second sidewall 48 from collapsing due to being weakened bythe formation of the plurality of drainage apertures 20. In oneembodiment, one or more sensors (not shown) may be provided at seconddistal end 44 of the second drainage tube 14. The sensor(s) may beadapted for measuring, for example, local blood pressure and/or oxygenconcentration.

The total cross sectional area of the plurality of drainage apertures 20is desirably approximately equal to or greater than the cross sectionalarea of the second lumen 46. If the cross sectional area of theplurality of drainage apertures 20 is less than the cross sectional areaof the second lumen 46, an undesirable pressure drop within the seconddrainage tube 14 may occur. This pressure drop reduces the flowthroughput within the second lumen 46 and impairs the efficiency of thesecond drainage tube 14. Desirably, the total cross sectional area ofthe plurality of drainage apertures 20 exceeds the cross sectional areaof the second lumen 46 such that if one or more drainage apertures 20becomes clogged, the total cross sectional area of the remainingdrainage apertures 20 is equal to or greater than the cross sectionalarea of the second lumen 46. In this manner, the blood flow through thesecond lumen 46 is maximized even if one or more of the drainageapertures 20 becomes clogged.

With reference to FIG. 7, the coaxial cannula 10 shown in FIGS. 1 and 2is illustrated in cross section. The second distal end 44 of the seconddrainage tube 14 is fixedly attached to a mid portion of the firstinfusion tube 12 along the length of second tapering section 50, asshown in FIG. 8. The first infusion tube 12 and the second drainage tube14 are coupled to the connector 22 in such manner that the firstinfusion tube 12 and the second drainage tube 14 cross inside theconnector 22 body without being connected to each other.

With reference to FIGS. 9 and 10, a detailed view of the connector 22 isshown coupled to a coaxial cannula 10 according to another embodiment.FIG. 9 illustrates the connector 22 shows the fluid pathways extendingthrough the interior of the connector 22. The connector includes adistal aperture 52 at a distal end of the connector 22 for connecting tothe proximal end of the coaxial cannula 10. The proximal end of theconnector 22 has the inlet portion 24 and the outlet portion 26 in fluidcommunication with the distal aperture 52. The outlet portion 26 mayinclude a barbed fitting 54 for connecting a drainage connection 57 thatextends to a blood pump. The inlet portion 24 includes an inner tube 56that extends through the interior of the connector 22 and connects withthe first infusion tube 12. The inner tube 56 may extend beyond thedistal aperture 52 for connecting with the first infusion tube 12. Adrainage opening 58 connects the second drainage tube 14 with the outletportion 26 of the connector 22. The drainage opening 58 is coextensivewith the inner tube 56 along the length of the body portion of theconnector 22. The inner tube 56 may be reinforced with a metal orplastic coil 60 that extends in a helical manner along the length of theinner tube 56 to minimize kinking and/or collapse of the first infusiontube 12.

With continuing reference to FIGS. 9 and 10, the inner tube 56 passesthrough the connector 22 to provide a smooth, seamless transition from asingle distal aperture 52 to the branched arrangement of the inletportion 24 and the outlet portion 26. The transition is desirably voidof any joints, welds, and other connections that can createirregularities in the flow of blood and can damage blood cells.

In use, the proximal end of the coaxial cannula 10 is connected to thedistal aperture 52 of the connector 22. The inner tube 56 receives bloodfrom a supply line 62 and sends it through the lumen of the inner tube56 to the first infusion tube 12. As the diameter of the inner tube 56is smaller than the diameter of the drainage opening 58, the inner tube56 extends through the interior of the connector 22, thus allowing theinner tube 56 to be continuous throughout the length of the connector22. Depending on the application, the inner tube 56 may or may notinclude structural reinforcement in the form of the coil 60. Inembodiments where the inner tube 56 is reinforced with the coil 60, theinner tube 56 is stronger and less susceptible to kinking or collapse.

The connector 22 may be made from polycarbonate as an example, but couldalso be made from PVC, acrylic, or polyurethane. The connector 22 may beconstructed using one or more manufacturing techniques includinginjection molding, machining, or dip forming. One of ordinary skill inthe art will understand that a variety of other manufacturing techniquesmay be used for constructing the connector 22 without departing from theintended scope of the invention.

With continued reference to FIGS. 9 and 10, one or both of the firstelongate body 28 of the first infusion tube 12 and the second elongatebody 40 of the second drainage tube 14 includes a helical coil 60extending through the length thereof. The helical coil 60 may bedisposed along the interior surface of the first lumen 29 and the secondlumen 46. Alternatively, the helical coil 60 may be disposed within thefirst sidewall 36 and the second sidewall 48. The helical coil 60 may bemanufactured from medical grade metal or plastic.

Having described several non-limiting embodiments of the coaxial cannula10 and the connector 22, an exemplary and non-limiting method forsupporting the right heart of a patient using the coaxial cannula 10 andthe connector 22 will now be described with reference to FIG. 11. Inuse, the coaxial cannula 10 is inserted into the pulmonary artery (PA)in a percutaneous procedure. The coaxial cannula 10 withdraws blood fromthe patient's heart and delivers blood back to the patient. Initially, apercutaneous entry needle (not shown) is used to access the patient'sinternal jugular vein (LTV). A guidewire is then inserted through theneedle until the tip of the guidewire is positioned in the upper portionof the inferior vena cava/right atrium (IVC/RA) junction. The needle canthen be removed and a pulmonary wedge catheter inserted over theguidewire into the PA. The guidewire tip is then threaded into the PA,and the wedge catheter is removed. The IJV is then serially dilated andthe coaxial cannula 10 is threaded along the guidewire into the IJV. Theintroducer can be removed when the coaxial cannula 10 is in the rightventricle. The coaxial cannula 10 can then be threaded over theguidewire up into the PA. The distal end of the first infusion tube 12is sufficiently flexible as to allow it to be easily flexed about thelongitudinal axis of the first elongate body 28. The coaxial cannula 10may include insertion depth markers and radiopaque markers for aidingthe user in placing the coaxial cannula 10 in the right atrium. A curvein the coaxial cannula 10 is a feature that helps it make the turn fromthe right ventricle into the PA. Once the cannula's position isacceptable, the introducer/guidewire assembly is removed and the coaxialcannula 10 is clamped. The coaxial cannula 10 is secured to thepatient's neck using a suture.

While several embodiments of a coaxial cannula are shown in theaccompanying figures and described hereinabove in detail, otherembodiments will be apparent to, and readily made by, those skilled inthe art without departing from the scope and spirit of the invention.

The invention claimed is:
 1. A dual lumen cannula configured tosimultaneously supply blood to a patient and withdraw blood from thepatient via a single access site of the patient, the dual lumen cannulacomprising: a drainage tube having a proximal end, a distal end, and alumen extending therethrough; an infusion tube coaxially aligned withinthe lumen of the drainage tube, the infusion tube having a proximal end,a distal end, and a lumen extending therethrough; wherein the infusiontube includes a distal end region extending distally beyond the distalend of the drainage tube to the distal end of the infusion tube;infusion apertures extending through a sidewall of the infusion tubenear the distal end of the infusion tube; and drainage aperturesextending through a sidewall of the drainage tube near the distal end ofthe drainage tube, the drainage apertures including first a first groupof drainage apertures longitudinally spaced apart from a second group ofdrainage apertures by a segment of the drainage tube without anydrainage apertures; wherein a length of the segment of the drainage tubewithout any drainage apertures is greater than a length of a segment ofthe drainage tube having the first group of drainage apertures; whereina distance between the distal end of the drainage tube and the firstgroup of drainage apertures is less than a distance between the distalend of the drainage tube and the second group of drainage apertures. 2.The dual lumen cannula of claim 1, wherein the first group of drainageapertures includes first and second circumferential rows of drainageapertures.
 3. The dual lumen cannula of claim 2, wherein the drainageapertures in the first circumferential row of drainage apertures arecircumferentially offset from the drainage apertures in the secondcircumferential row of drainage apertures.
 4. The dual lumen cannula ofclaim 1, wherein a spacing between adjacent ones of the drainageapertures in the first group of drainage apertures is less than adistance between the first group of drainage apertures and the secondgroup of drainage apertures.
 5. The dual lumen cannula of claim 1,further comprising a third group of drainage apertures longitudinallyspaced apart from the first and second groups of drainage apertures,wherein the second group of drainage apertures is positioned between thefirst group of drainage apertures and the third group of drainageapertures.
 6. The dual lumen cannula of claim 5, wherein the aperturesof the second group of drainage apertures are circumferentially offsetfrom the apertures of the third group of drainage apertures.
 7. The duallumen cannula of claim 5, wherein the second group of drainage aperturesis positioned longitudinally closer to the first group of drainageapertures than to the third group of drainage apertures.
 8. The duallumen cannula of claim 1, wherein the infusion apertures include firstand second longitudinally spaced apart rows of infusion apertures. 9.The dual lumen cannula of claim 8, wherein the apertures of the firstrow of infusion apertures are circumferentially offset from theapertures of the second row of infusion apertures.
 10. The dual lumencannula of claim 1, wherein a distal end region of the drainage tube hasa tapered portion extending distally beyond a distal-most aperture ofthe drainage apertures to the distal end of the drainage tube.
 11. Thedual lumen cannula of claim 1, wherein a distal end region of theinfusion tube has a tapered portion extending distally beyond adistal-most aperture of the infusion apertures to the distal end of theinfusion tube.
 12. The dual lumen cannula of claim 11, wherein an innerdiameter of the infusion tube and an outer diameter of the infusion tubeboth taper in a distal direction in the tapered portion of the infusiontube.
 13. The dual lumen cannula of claim 1, wherein a totalcross-sectional area of the infusion apertures is equal to or greaterthan a cross-sectional area of the lumen extending through the infusiontube.
 14. The dual lumen cannula of claim 1, wherein a totalcross-sectional area of the drainage apertures is equal to or greaterthan a cross-sectional area of the lumen extending through the drainagetube.
 15. The dual lumen cannula of claim 1, wherein the infusion tubeincludes a reinforcing coil extending therethrough.
 16. The dual lumencannula of claim 15, wherein the drainage tube includes a reinforcingcoil extending therethrough.
 17. The dual lumen cannula of claim 1,further comprising a connector provided at the proximal end of theinfusion tube and the proximal end of the drainage tube, the connectorincluding an inlet portion defining an infusion fluid pathway in fluidcommunication with the lumen of the infusion tube and an outlet portiondefining a drainage fluid pathway in fluid communication with the lumenof the drainage tube.
 18. The dual lumen cannula of claim 17, whereinthe infusion fluid pathway and the drainage fluid pathway transitionfrom a coaxial arrangement at a distal end of the connector to anaxially offset arrangement at a proximal end of the connector.
 19. Adual lumen cannula configured to simultaneously supply blood to apatient and withdraw blood from the patient via a single access site ofthe patient, the dual lumen cannula comprising: a drainage tube having aproximal end, a distal end, and a lumen extending therethrough, thedrainage tube including: a first group of drainage apertures extendingthrough the sidewall of the drainage tube along a first segment of thedrainage tube; a second group of the drainage apertures extendingthrough the sidewall of the drainage tube along a second segment of thedrainage tube proximal of the first segment; and a third segment of thedrainage tube extending between the first segment and the secondsegment, the third segment being without any drainage apertures; whereina length of the third segment of the drainage tube is greater than alength of the first segment; an infusion tube coaxially aligned withinthe lumen of the drainage tube, the infusion tube having a proximal end,a distal end, and a lumen extending therethrough; wherein the infusiontube includes a distal end region extending distally beyond the distalend of the drainage tube to the distal end of the infusion tube; andinfusion apertures extending through a sidewall of the infusion tubenear the distal end of the infusion tube.
 20. The dual lumen cannula ofclaim 19, wherein the first group of drainage tube includes first andsecond circumferential rows of drainage apertures.
 21. The dual lumencannula of claim 20, wherein the drainage apertures in the firstcircumferential row of drainage apertures are circumferentially offsetfrom the drainage apertures in the second circumferential row ofdrainage apertures.
 22. The dual lumen cannula of claim 19, wherein theinfusion apertures include first and second longitudinally spaced apartrows of infusion apertures.
 23. The dual lumen cannula of claim 22,wherein the apertures of the first row of infusion apertures arecircumferentially offset from the apertures of the second row ofinfusion apertures.
 24. The dual lumen cannula of claim 22, furthercomprising a third row of infusion apertures longitudinally spaced apartfrom the first and second rows of infusion apertures, wherein the secondrow of infusion apertures is positioned between the first row ofinfusion apertures and the third row of infusion apertures.
 25. The duallumen cannula of claim 24, wherein the apertures of the second row ofinfusion apertures are circumferentially offset from the apertures ofthe first and third rows of infusion apertures.
 26. A dual lumen cannulaconfigured to simultaneously supply blood to a patient and withdrawblood from the patient via a single access site of the patient, the duallumen cannula comprising: a drainage tube having a proximal end, adistal end, and a lumen extending therethrough; an infusion tubecoaxially aligned within the lumen of the drainage tube, the infusiontube having a proximal end, a distal end, and a lumen extendingtherethrough; wherein the infusion tube includes a distal end regionextending distally beyond the distal end of the drainage tube to thedistal end of the infusion tube; infusion apertures extending through asidewall of the infusion tube proximal of the distal end of the infusiontube; and drainage apertures extending through a sidewall of thedrainage tube proximal of the distal end of the drainage tube, thedrainage apertures including first, second and third circumferentialrows of drainage apertures; wherein the second circumferential row ofdrainage apertures is located between the first and thirdcircumferential rows of drainage apertures; wherein the firstcircumferential row of drainage apertures is located closer to thedistal end of the drainage tube than the second and thirdcircumferential rows; wherein a longitudinal distance between the firstand second circumferential rows of drainage apertures is less than alongitudinal distance between the second and third circumferential rowsof drainage apertures; and wherein the distance between the second andthird circumferential rows of drainage apertures is without any drainageapertures.
 27. The dual lumen cannula of claim 26, wherein the drainageapertures in the first circumferential row of drainage apertures arecircumferentially offset from the drainage apertures in the secondcircumferential row of drainage apertures.
 28. The dual lumen cannula ofclaim 27, wherein the drainage apertures in the third circumferentialrow of drainage apertures are circumferentially offset from the drainageapertures in the second circumferential row of drainage apertures. 29.The dual lumen cannula of claim 27, wherein the infusion aperturesinclude first and second longitudinally spaced apart rows of infusionapertures.
 30. The dual lumen cannula of claim 29, wherein the aperturesof the first row of infusion apertures are circumferentially offset fromthe apertures of the second row of infusion apertures.